Ionic liquid mediated synthesis of graphene–TiO2 hybrid and its photocatalytic activity

Highlights: • RGO–TiO2 hybrid was efficiently prepared in a solvent of ionic liquid–water. • TiO2 nanoparticles had well mixed on the RGO surface. • RGO–TiO2 hybrid with RGO/TiO2 ratio of 1:3 showed excellent photocatalytic activity. • The method reported here is a green route suitable for large-scale production. -- Abstract: A graphene–TiO2 hybrid was synthesized by a solvothermal microwave-assisted method in a mixture of two green solvents: water and an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4]). Graphene oxide (GO) could be easily reduced under microwave irradiation without any additional reducing reagent. Titanium (IV) isopropoxide was used as a starting material for the growth of TiO2 nanoparticles on the graphene sheets accompanied by the reduction of GO. The structure and morphology of the as-prepared hybrid were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermogravimetric analysis. The graphene–TiO2 hybrid had a high surface area and exhibited high photocatalytic degradation of methylene blue